Automatic telephone-exchange system.



W. R. BINKLEY.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 22,1905.

1,093,525. I Patented Apr. 14, 1914.

- 9 SHEETS-SHEET l.

31 l newton @7 ,GL J a W w. R. BINKLEY. AUTO MATICTELEPHGNE EXCHANGE SYSTEM. APPLICATION FILED JULY 22,1905.

Patented Apr. 14, 19% I 0 SHEETS-SHEET 2.-

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Wits imam W. R. BINKLEY.

AUTOMATIC TELEPHONE EXCHANGE SYSTLM.

APPLICATION FILED JULY 22,1905.

Patented Apr. 14, 1914.

9 $HEBTS-SHEET 3.

Wit" 090,:

w W. R. BINKLEY. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 22,1905.

1,093,525. Patented Apr. 14, 1914;

9 SHEETS-SHEET 4.

W R. BINKLEY.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 22,1905.

1 ,093,525.. Patented Apr. 14, 1914.

a sEEETs-sHBET a.

W.-R. BINKLEY.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APVPLIOATION FILED JULY22,1905.

1,093,525. Patented Apr. 14, 1914.

9 SHEETS-SHEET 8.

W. R. BINKLEX. AUTOMATIG TELEPHONE EXCHANGE SYSTEM. APPLIBATIbN FILED JULY 22, 1905 1,093,525. Patented Apr. 14, 1914.

. QBHBETS-SHBET '1.

3 I wanton Witwtma W. BINKLBY. UTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 22,1905.

Patented Apr. 14, 1914.

a mama-sum a.

Witness W. R. BIHKLEY. AUTOMATIG TELEPHONE EXCHANGE SYSTEM. AI'PPLIGATION FILED JULY 22,1905

1,093,525- Patented Apr. 14, 1914.

9 SHEETS-SHEET 9.

UNITED PATENT OFFICE.

WILLIAM RAGAN BIJNKLEY, OF NE\V BEDFORD. MASSACHUSETTS, ASSIGNOR OF ONE- HALF T0 EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Apr. 14, 1914.

Application filed July 22, 1-905. Serial No. 270,852.

T 0 all w/iom it may concern Be it known that I, VVILLIAM'R. BINKLEY, a citizen of the United States, residing at New Bedford, in the county of Bristol and State of Massachusetts, have invented cer-.

operation may be improved and the appa-- ratus simplified;

In its broadest aspect my system..comprises a percentage trunking schemefthat is, it employs a trunk selector or A switch for each line, whose sole function is to seize upon and temporarily connect its line when calling, with an idle trunk and first selector switch, which in turn will select and seize upon other idle switches in desired groups,

there being a smaller number of these selector switches than there are lines, the successive groups bearing a definite percentage relation to the number of lines. Thus, of first selector switches I may employ five per cent. or ten per cent, or in very busy exchanges even fifteen per cent. (the total number of subscribers lines being taken as one hundred per cent). Of second selector and connector switches I may employ the same percentages. Selection of any desired line is made, first by causing the A switch of the calling line to seize upon an idle first selector switch; then through this first selector seizing upon an idle second selector in the desired thousands group; then through this second selector seizing upon an idle connector in the desired hundreds group; then through the connector effecting contact with terminals in the desired tens group and finally the desired terminals in that group: then testing these terminals to ascertain if the line wanted is busy; then f the ubsc'ribau wanted is on a party-line, selecting the proper current to ring his station; and finally to send such current to line. This currentv is sent over what I call the private normal wires, and upon examina tion of my circuits hereinafter described, itv

will be observed that I have found means to enable a subscriber to ring back upon his own line and call another subscriber on that current himself, and without his telephone interfering with the ringing current. From this general statement it may be seen that the basis for" my system is a percentage trunking armngeiiifinlt the success of which has been fully demonstrated in commercial practice, and to which I have added A switches (or line switches) which effect-the initial connection between calling lines and the trunking net work, selective party-line ringing means, a scheme for mechanical deyelopment and simplification of the switches,

'ments, together with relay and magnet windings required thereby, all of which will be fully described hereinafter. I also attain, however, the difficult ends of giving party-line service and employing a common battery as the source of current supply for all purposesl I shall present herein a, design for a switch which I desire to have taken as typical only. Such switches are always modified after having been used awhile. and I am aware that many details may and probably will in course of'timeundergo change. Nevertheless, the distinguishing features of the type I consider characteristic, and that they will be permanent. In this switch I employ four principal magnets, and in connect-ion with each two 'relays. The contact arms or wipers have a rotary 'n otion only, there be of wipers and three banks of contacts are employed. Set No. 1 effect the selection,

set No. 2 effect the test and also shift a common actuating magnet mechanically from set No. 1 to set No. 3, the latter then admiring until an idle trunk of the selected group is reached. The test, sets of the A,

B and C switches have three possible posi-.

tions, one being normal, the second an extreme position for test, and the third an' hub, the No. 1 wipers are mounted on another line, without" netting any ofthe ringing and certain circuit connections and arrangemg no double motion employed. Three sets 7 trance to the second coil.

common hub, and the No. 3 wipers on still another common hub. Each set of wipers moves together as a unit, and it is by interconnection fromothe wipers of one set to the bank contacts of another set in the same switch that I am enabled to avoid the use of separate movements and mechanical parts. To put the mattervin a word, instead of having the same wiper step up and then around, with two motlons, as in the Strowger system, I have two sets of wipers which act in succession and cooperate to produce, the same result.- Moreover,'I only employ one stepping magnet for both movements, mstead of two as heretofore.

An important feature of my invention, es-

pecially considered with the common battery feature, is the employment of a two-wire e1r cuit. Of course, it is necessary in any Sus tom of this kind to provide for distingu/rsm ing between working impulses and what I may designate as control impulses. The working impulses are transmitted oyer the circuit in groups of ten or less,wh1Ie the control impulses serve to change the connections during the intermissions between the groups of working impulses, so that each group may reach, the'particular apparatus for which it is intended. In the Strowger systems and others the control impulses are sent over one side of the line and the workin impulses over the other, the necessary shifting being effected by means of What is called a side switch. I supply current to both sides of my line from the common battery for the transmitter at thesubstation, which then propagates voice currents into the metallic circuit through the medium of an induction coil; and in order to difi'erentiate between the signal impulses I divide them into those which require both sides of the line to be grounded (or working impulses), and those which require only one side of line to b'e-grounded' (or controt impulses), and finally those which require the 'other side of line to be grounded (or gelease impulses). 'Toattain my ends I employ differentially wound relays of novel and peculiar type, which I shall claim 'hereinafter. One of these relays has a pair of differential windings included seriatz'm in a branch metallic circuit from line to battery. Another of these relays has three equal windings, one of which is individual to one side of the branch metallic circuit from line to battery through a second or common coil. The third coil is individual to the other side of the branch metallic circuit from line to battery also through the second or common coil, joining the first at a common point of en- The connections of these windings are such that the individual and the common coil from one side are reversed to each other as to magnetic effect,

while from the other side the individual and.

common are in the same uirrction as to'magncti'c effect. The individual coils of this-relay form a second differential relay in series with the first or plain differential relay, which when taken together form a bridge to the metallic circuit of very high. magnetic reactance to'high frequency currents, and a balanced circuit to direct current, flowing over both sides to supply the primary of the transmitter.

The first relay I employ for'testing, and the second one for working the sw tches. \Vorking im-pulses are sent over both sides of affect the plain differential test relay, but do aflfect the working relay, since the individual 'COllS only oppose each other, while the-comboth lines and is effective.

For testing purposes, I ground that side of the line which contains the balanced windings of the working relay, whereby the test relay becomes energized, while the working relay remains idle. For the purpose of restoring the apparatus to zero or normal position throughout, I ground the other side of the line in, ..-'hich the individual coil and r the commorrcpi; of the working relay act to anther magnetically, whereupon both relays (become energized and by. their joint action close the release circuits. Each switch has these two relays, the working magnetfthe shifting magnet. the selecting magnet, the test magnet, and this. release magnet, all of which will be fully described hereinaftee.

The method of selective ringing is simple but exceedingly effective, and I consider it to be broadly new. It consists in providin on the connector switch an extra pair 0 wipers which move with the selecting Wipers, and a sct of bank contacts connected to the various generators, employed. The line to cover one or more corresponding generator contacts in point of angular dimensions. Thus, a line may come in and have a broad contact over which the wiper will have to next contact. The underlying wiper passes over four different terminals during these four steps, and obviously I may put four pa ies on the line, giving them successive numbers, and ring them sepa rately, .since successive steps will supplydifierent generator currents to the line. There may be one, two, three or four party contacts in the same bank, and the current supplied mined ,by the underlying generator bank contacts. Moreover a great saving in the 'wiring in the connector banks is effected, as. well as the saving of a largepercentage of the connector switches. requirfld by most of the automatic systems giving party-line service. F or'example, for a four-party line make four steps before it passes on to the when those lilies are selected will be deter-' the lines simultaneously and hence do not 7 mon coil receivesthe united current from contacts a're'made of various lengths, sons f only one set ofcontacts is required .in each bank or in each connector' switch ofthehun- 'dreds, group containing". the line number. Since one connectorsupplies the; four kinds eirmging current, obviously there 11:8 both a great saving of-connector switches-in system over other systems requiring;quad ;mple:.gro i 1ps of connectors, each adapted tosupply: but one" kind- :of ringing current to the same lines Furthermore there is .a

'great fl exibility in my party-line connector.

In 'a connector 'toserveone hundred sub scribers, I'may assign one horizontal row of ten sets of bank contacts for unes: or fortysubscrib'e'rs: in all. apa-rt' the next two horizontal rows -t aining ten sets of-bank contacts, for twoparty lines, ora totalof forty subscribers; @an'd'lastly I may have two other rows con taining four-partyf I may set each c'onten sets each of bank contacts, foror a total of twenty subsingleparty lines, I

'. This gives a grand total of one,

scribers.

' hundred subscribers bin: fifty sets'of bank contacts, all handled by one connector-or a percentage group of similar connectors.

'I put my ringers in ground taps, in the drawings herewith, but they may be in metallic circuit bridges; and of course durin a through connection Lhave a metallic talking circuit right through from subscriber to subscriber, with a bridge acrossit how- 'ever at every switch, or four bridges in all.

In each bridge, however, there is a high im-. pedance, for be it observed that the differential windings of my relayswhich are'inthe bridges, do not neutralizethe magneticre actance for high frequency currents, al though they do destroy the magnetic effects for battery currents. Moreover,-'four bridges are permitted by standard practice in manual systems.

--Myinvention is illustrated in the accom- Figure 1 shows four subscribers statgions connected tothe same line These stations receive party-line service and are shown diagrammatically, the sender or transmitter device in each case being represented for convenience by push buttons instead of the ordinary transmitting device; Fig. 2 represents what I, shall call the A switch,='therebeing one of thesefor each subscribers line; Fig. 3 shows the first selector-or B switch; Fig.4 shows the second selector or'G-switch'; Fig'. 5 shows the connector or D switch; Fig; 'Gshows the means for picking out a certain generator current for I selective partyr-line work; Fig. 7 is a side elevation -/o f the'B switch; Fig. 8 is a side view of the- 'switch, showing the magnet O and the parts actuatedft; rebyilooking from the-1 left in, Fig, 11; F g.' '9 -ifs a side view of'the same magnet with its iattached arts -pro ected on the end of the'iram'e; 1g. 10 is a longis". shown in F g.

acts as the. release button 11; Fig. vl1 is an elevation sliowingthc several magnets and the parts actuated-thereby.

' Referring first. to Fig. 1, -wherein four party-line stations, K, K, K K3 are shown, the apparatus at all being identical. the variousparts will be designated through out by the same letters or'numerals. Re-

ferring particularly to station K, the telephone set proper consists of the transmitter T, receiverR, induction coil'fl, retardation coil N, ringer Q, condensers-TL, L, and hook One terminal of'thetransmitter is grounded, the other terminalfibeing con nect'ed, when the hook H is up, to both. sides .of the line through the twoiwindings'ofthe retardation coil N'and the-,priinarfof theinduction coil I. Push-button P of the transmitting device when depressed grounds No- 6 side of the line to operate the tr nk. magnets of the various :switchespthe push-button P grounds bothsides of the line simultaneouslyto operate the switching relays for the various switches; the push- --.b.utton.P grounds No. 5 side of the line 'and I for the various switches; the push-button P when'depressed vdisconnects the ground through. coil N from both sides of the line by opening the trans' mitter circuit which actuates the ringing relay in the D or connector switch. Station K is shown as acalling station, the receiver being removed from the hook.

Before entering into a detailed description and statement of operation of the several dilferent switches and their circuits, the following distinction between them should. be carefully noted: The B and C switches-Aireidentical and are group as ,well as ,i dle trunk selectors. vOn theother hand, .tli function ofthe A switch is that. of an idle trunk selector only, since its sole function is to. connect its line when calling with an'idle first selector. 7 Consequently it is without,

the set of bank contacts designated as Se- 'ries l in the B, 'O and D'switches. Re- 11 ferring to Figs. 7, 8 and 9, 'itghas-already been stated that the mechanical features shown are intended to represent a typebi mechanism adaptable to the purposes o. each ofthe switches in thes'ystem, illld'IlOll-El 1 fixed and unchangeable specific design; "The ,aswitch wouldnot require the No. '1 banks at the right of F ig: 7 nor theoperat ing ratchet, pawl, or arm therefor; neither necting mechanism; neither would it require a heavy operating magnet'as shownat-O, a single magnet- V being probably suifici'ent, Thus in design the ,Aswitch can be'made, small of. very simple, construction, since 's,ries which represents the banks of the five or ten pairs of trunks leading tov the first selector switches. are all that are required-for selective purposes. The magnet X in th is switch may well combine the dou- 130 would it require the slide bar 8 nor. its con- 12 ble function of "testing and trunking. ,Again, the connector switch D is the' same as the B or C 'switchps, but'stripped of its trunk selective function and made to operate ,5 series 3' by impulses sent from the subscrib'ers station through an additional function of series 2,- instead of by interrupted current supplied from C, G or C--. It also containsthe ringing current selective bank .iqshown as series 4.

Referring now to Fig. 2, the A switch con- .sists of the -icllowing: the relay M, which has two windings,- a terminal 'ot one windline, and the other terminal thereof being connected to theterminal of relay E; a terminal of the second winding,m is connect ed, to No. 6Jside of the line, the other terminal thereof-being connected to "a second ;2o"termina-lof the relay E. The relay E itself as would be the case whensimultaneous im pulses are sent over both line wires 5 and 6, there Wlll of course be a lack of balance, and

ized by acurrentequivalent in ampere turns to twice that of. any one ofthe three windings, when two'of them are Connected in series. I consider this relay windings 40 ,very important feature of my invention, and shall claim it broadly-as well as specifically. I believeI- am the first to provide means whereby current through one side will not energize a difi'erential relay, but that -15 through both sides will do so. I'use this presently appear. The relay M has two equal windings, m", "m and unlike the relayE it remains in .a neutral state while current is flowing over principle throughout my system, as will both sides of the line simultaneously and isoperative or becomes energized while current is flowing over either side of the line at ditl'er'ent intervals. The trunking magnet V 5 is operated when the relay M is energized, by the closing of the contacts m and m, and this magnet V in turn causes the wipers of series marked 2- to move from what I shall I call the a or normal position to what I shall "call the 0 position, which is a trunking or test position. When the relay M becomes deenergized after a certain interval the wipers of series 2 fall back and rest in the 1) position where they remain throughout conversation. All the wipers of the various ing', m -,.'being connected to No. 5 side of the,

feet but with current-through all three coils,

hence the core of the relay will be magnetseries and 3 normally rest'on the first .contacts of their respective banks, the advantageoi' this. being that if the first contact is not engagedbysome other party there will beno movement of the switch necessary. Bearing in mind also that all. of the B switches of the group to which they belong have their similar contacts of series 1 in multiple, it will then be seen that when series 2 occupies the 6 position all the similar contacts in the test 'set of series'1.that are multi'pled in the switches of the group will he grounded when brought in'contact -with wiper 2 a 7 Z12, 7 In a similar manner the multipled test contacts of series 1 of switchC are grounded through wiper z, 57, z, 71 2, 6,67, 68', ground. Those of switchD will likewise be grounded through wiper 2 85, 2f, 100, 2 C (this being the position for conversation), 88, 95, ground. In order to simplify the description, I have shown the test contacts inseries 3 of the-switch A, and in series 1 of the switches B, C, and D as being directly con- 'nected to ground, this being theircondition wheh the switches are busy as described. Now when the wipers of the series 2'are in the '0 position and the first contact opposite .2 in series 3 happens to be busy or grounded the test magnet X becomes energized 5 through the following circuit: ground, a 26', 2', l3, X, '21, battery B'and ground. The magnet X then becomes energized and causes the'wipers 2 2 and a of series' 3 to step around until an idle contact is found. The release magnet, W, is connectedon one side to contact m and on the other to-contact a so as to be actuated when the relays M and E are energized at the same time; This only happens at the end'ot a conversation,

.when'the calling subscriber presses his button'P (Fig. .1), and grounds No. 5,side of the line. The relay E is kept energizedduring conversationby battery flowing over both sides of the line through the transmitter to ground. Its armature remains at tractedand breaks the contacts e e and e*e protecting the calling subscriber from interruption while talking to anyone, whether on his own or some other line. The 1 wipers z and 2 of series'2 terminate in contacts in the banks vof the connector switch of their particular group and are the pri vate normals. In this case I have used five per cent. of connector switches so therefore the linesfrom each station will terminate in their own individual A selectors and the private normals will be connected in multiple to the contactsof the fiveconnector switches each of its particular group.

Referringnow to Fig. 3, theB switch consists of the following: relays M and E, which operate in thesame manner as relays M and E in Fig. 2.}The relay E controls the operating magnet O which in turn o,-

side of battery.

the number of impulses sent in over both l sides of the line sin'iult-aneously affecting the ';r'elay E. The magnet O is operated by the relay E by the following circuit: battery -13, O, 50, ,2 (1-, 40, e, 6 -6 to the opposite The relay 'M is operated by ground being placed on No. 6 side .of-the line as in Fig. 2, and in turn operates the magnet V which causes the wipers of the series 2 to take the 0 position. The B switch picks out the thousands numeral of the line desired, When the wipers 2, 2 and. a of series 1 come to rest on the con tats-corresponding to the number of impulses of the desired line they are connected with the five trunks of the desired thousands in the following manner: The series l is made up of five rows of contacts, each now having three wipers, best shown in Fig. 7. These wipers movein unison. The first contact of the first row is connected to the first trunk' leading to the on'ethousand group; the first contact of the second row is connected to the second trunk leading to theone thousand group; the first contact of the third row is connected to the third trunk leading to the one-thousand group, and so am. The second contact of the first row is to the first trunk leading to thetwo-thousand group and the second contact of the secondrow is connected to the second trunk leading tothe two-thousand group and so on up to the ten-thousand group, The wipers of the first row are con= nected to the first contacts in series 3, and ,the wipers of the second row are connected to thesecondcontacts in the same series. It will readily be seen that when the wipers in series 1 rotate a certain distance, say

three spaces, the wipers will restonthe five trunks leading to the three-thousand group, but without effect asyet, since theyall reomain on open circuit until the wipers in series .3 rotate and pick out one of the trunks which is not busy and close the circuit of the trunk selected. For illustration;

suppose the wipers in series 1 had moved to .the three-thousand group and that the first trunk was engaged orbusy, then a ground would be placed opposite the test wiper 2 and the test magnet Xv would. have its'cir- .cuit closed and (through the actuation of aha-the operating magnet 0) cause the wipers in series 3 to pass the busy contact and take the next one which is not busy. The circuit .of the magnet X is closed through the following pathz ibattery B, 41, X, 49, 38, c, 2 14,2 33, 2 to ground. In attracting its armature it closes the contacts and :n' which in turn close the circuit of the magnet 0 by the following path: battery B, 41,

a x, and :v, 39, c, 2 50. O, to the opposite side of battery. The magnet 0 now causes the wipers of the series 3 to rotate and come opposite contacts leading to an idle trunk. It will be noticed that in the first operation the magnet 0 causes the rotation of series 1. but now it causes the rotation of series 3 alone. After the trunking period the magnet .\l' hcconics dcnergized, which in turn dciincrgizcs the magnet V allowing the wipers in series 2 to assume the (a position. The calling subscriber is now connected to the C- switch. This switch picks out the hundred numeral of the desired line and being identical with the B switch in Fig. 3 need not be described.

Referring now to Fig. 5, the connector switch D is shown. which consist-sof the following: dili'crentially wound relay E which responds -to impulses sent in over both sides of the line simultaneously and which in turn controls the operating magnet 0 which successively controls series 1, 3 and l. The relay E unlike the relays in the selector switches is'operated twice. that is. it transmits first the tens numeral and after that the units numeral. This is brought about by strapping the terminals a and I) together in the series 2, so that after the wipers .2 and 2 move one space they still have the same connection. The relay 11. when actuated over No. 6 side of the line. energizes the relay V by closing the ergizing of the relay V makes series 1 inoperative and series 3 operative by the magnet O After the operation of the tens numeral the spring wipers with reference to the bank of contacts are disposed as shown in Fig. 6 at (1', (Z (Z (13* and d rcsting on the tenscontact of all the numbers in a certain hundred.

A bank of contacts'in the sense here intend ed, consists of a numberof contacts arranged in a plane or planes at right angles to an axis and at a predetermined distance apart and from the axis. so that spring wipers attached to a shaft rotated in the axis will come successively into contact with separate contact units in the plane. In my bank there are five such planes with thirty contacts in each. There are also fire sets of three wipers each mounted on the shaft. one set for each plane of contacts. Thc'thrce wipers of a set are placed at an angular distance apart subtendiug an arc of ten contacts. Two of the contacts are trunks or lines. and the third the test contact. in each set of three.

In Fig. T. series 1 shows a section in a plane passed through the axis, the contacts being shown in full lines, and the insulation in section. In Fig. 6 I-have shown the five horizontal planes of contacts spread out in one plane together with the winers of each,

and designated them by the symbols d, (1 03 d, d. Thus is series 1 shown complete. Above these in the length of the sheet or on the right of the figure, I have placed series?) and 4, consisting of but two planes of contacts and wipers. I have arranged them in this order so as to better show their relation, the one to the other. It will be observed that when the shaft is rotated the five sets of wipers will at every step occupy similar or corresponding contacts. It follows that after the operation of the tens-numeral the spring wipers with reference to the bank of contacts are disposed as shown in Fig. 6 at d, (P, (i cl, cl, resting on the tens contacts of all the numbers constituting this bank of contacts. When the impulses representing the units numeral are transmitted over lines 5 and 6, and magnet O is actuated thereby,

the wipers of series 3 and 4 of Fig. 6 will be advanced by as many steps as the-units numeral represents.

. By the arrangement of series 3 beingsupi1ed with broad contacts embracingfour positions it is evident that the line connecons will not be changed for the first four successive impulses. The line contacts will be contained in the section d and each pair of contacts will represent a four-party line. Again referring to series 3, Fig. 6, it is seen that the next two positions would be embraced in the contact connected with section (i and that each pair of contacts would represent a two-party line. Likewise thenext two contacts of series 3 would be embraced in. a broad-contact similar to the two preceding ones and connected with section cl The last two'contacts of series 3 are single and connect with d and 03 respectively, representing single lines. The selective ringing current for these several differentlines is selected as follows: Series 4 of Fig. Gshows the method of selecting one of four different kinds' of ringing current, which may be pulsating or current of different frequency.

.The first pair of contacts lead to one generator of a certain frequency, the second pair to a generator of another frequency, and the third and fourth pairs-to similar generators of different frequencies. In the connector I or D switch series 3 and 4 are in one bank 1 and the wlpers for the same move 1n unison occupying similar positions at the same time. This being the case it will be'readily seen that the wipers 2-" and 2-, of series 3, will .remain unchanged for the first four impulses of the tens numeral, while four dif ferent ringing currents are supplied to the contact of the ringing relay Y indirectly connectedwith the lines5 and 6 through 101, 102, 86, and 87. In the same manner for the next two contacts in series 3' two different ringing currents will be supplied and also for the next succeeding two, while the last two contacts will bestipplied with one kind only. It will be seen from this that provision has been made for forty four-party, forty two-party and twenty single party operates series 3 corresponding to the unit-- numeral of the line desired. After the unit numeral has been sent in impulses are sent in over No. '6 side of the line, affecting the relay M", which in turn operates the trunking magnet V which advances series 2 to the 0.- pcsitlon. After a certain interval allowing 'for a test to be made for a busy line, series 2 assumes the ,0 position in the same manner as the selector. switches -assume the 6 position. If the line is busy the following conditions will prevail: The contact occupied" by the wiper a will be grounded by some switc ii occupying some multiple of itrenderingit busy, and then the following circuit be com-- pleted: ground, z, 85, 2. 100, 2 (l, 89, (Z, 2 104,1), 71 -105, 90, V", 94cm This circuit will be maintained after the battery Bl,

trunking period is terminated, that is'after the ground connection from No. 6 side of line at the telephone is broken and will be maintained so long as the line is 'll9l(l busy.

While this is held busy we harethe follow- 6 mg indication of it: G is a generator or busy-back producing a characteristic soundto act as a busysignal to the calling subscriber. This signal is conveyed to the calling subscriber by the following circuit: ground, G 98, '0, '0, 103, 2 d, 86, 'e y L, 82, 55, through the switches C, B and A to ground through the calling subscribers telephone; The ringing relay isoperated' after series 2 has assumed'the 0 position and the calling subscriber disconnects ground from both sides of the line by pushing the button P which opens the transmittercircuit. The relay E as well as the similar relays 1n the selector switches, becomesdcenergized, the armature of the relay E fall-v ing 'back closing the contacts e and e,

which closes the circuitof relav Y by the following path: battery B, 94, Y, 99, c, 2",,

96, m, 97, e", e, .95 to the opposite side of battery. The relay Y when energized for. ringing opens the contactsy", 3 f and 1 opening the line of the calling subscriber to prevent generator current being sent back.

In the case of calling a party on the same line, generator'current is sent back to the calling line over the private normals by the following path: 86, c, 2. 103, 11 2 0; 102.

z, 84, 2 private normal 24; andin. Fig. 2,

e 9, e 6:, 8, line'No. 6 through the called subscribers ringer to ground, The release magnets W, W, W and W are perated when the called subscriberdepresses the release button. which grounds No. side of the line. energizing the' pair 'of ditl'erentiall wound relays in each switch. thereby closing 5 the circuits of their respective release mag-' nets. j

In Fig. 7 I have shown a selector switch B to'ope 'ate in connection with the foregoing-circuits. 'lVhile this switch fulfils 'all the necessaryconditions, I do not wish to be limitedto the exactconstruction. as I have statedheforef A switch can be designed in various ways to embody and render useful the principle'ofmyinvention. It will he recognized at once the switch has but one motion. \'iz.. a rotary motion. consisting, however, of the successive rotation of wiper series 1, 2 and in their order. These series correspond to those similarly nmnhered in the other figures. The operating magnet- O has the double arms .sand s carrying the V engaging pawls s. s". respectively, which when in proper position engage altermltely the toothed hubs s and a. causing the rota-- tioiro'f series l or 3. as the case may be.- .ll'hen the magnet V is energized it draws down the armature carrying the 111118 which supports the pawl 8 The pawl en- 1 gages the tooth s of the wheel 8* and draws itdown a certain distance and turns the wheel s. To the spindle of the wheel 8* there is fixeda' crank arm s". carrying a guide 8 On the under face of this guide are two projections, best shown in Fig. .10. One of these projections, when'the wheel 8* is in the'normal or a. position. permits the pawls to engage the hub s which actuates series. 1. The'other projection comes in the path of the pawl 8 when V is energized and 8* isrotated intothe c or test position. In this position.'thc projection which normally engaged s is now out of engagement, leaving this pawl inoperative with reference to its hub s. In the'connector switch the wheel 8*, has two teeth s and s. The tooth a -is situated'below the position of the tooth s. when the,\\'heel is in its normal position. at such 'a distance that when the pawl -s" of the-connector switch is operated it does not engage the tooth 8 until the latter part of its movement. This results in turning the wheel s and the wipers carried thereby one) space instead of two. The arm 8 and the bar s however, are arranged to be- 56 shifted during this one step. A subsequent actuation of the arm .9 engages the tooth s which is so placed on the wheel s that the latter is moved two spaces. It will be observed that 1st, series 1 will be operated 60 while the wheel ,9 is in the normal position,

a, and 2nd, that series 3 will he in the operative position when the magnet V is energized, i. 6., whe 1 the wheel 8 is in the 0 position. After. the magnet V is denergi'zed. the pawl s en a es the tooth s, which allows the wheel to drop back just one space. or .to the 7/ position. instead "of allowing t to fall'hark to normal or the n lt'l li. The wipers of series 1 are opcralul-upon the movement of the shaft s to which the toothed huh x" i: rigidly lixed. lhe aiipcrs of series 3 are mounted on the sleeve s moving freely on the haftlmt lixed rigidly to the toothed huh a. The operating magnet performs two iu'nrlioi'is: It operates series 1. and also operates series I). depending only upon the guide arm carrying the projections to cause the proper pawl to en gage its respective huh. ()u theend of the 'fral'ne are ll()\\'ll the dillercutially w und relays E and M. p r

Figs. 8. 9 and 10 showthe operation of the two pawls \'er clezu'ly. Fig. '10. while merely fragmentary iu itselt'. jshows the guide r slide bar 8'' together with the cam projections which engage the two'pawls and force them alternately into operative.rclatlon with their respective gears. The re:- lease magnet ll" worksto releaset he switch on the break. that is to say. when energized by a pulse of cnrrent. it pulls up its armature and a hook pawl carricd'therchy passes up over the horizontal linger ot' the dcte nt pawl. pulling down and "releasing the lat ter when the current impulse ceases. This is a necessary condition for positively releasing switches in series in mostsystems.

'If any switches were released on the make- .lnstead ofthehrcak. they might cut oti'those.

heyomlhefore their magnets had a chance to work. but by making the release on the break. all the magnets 'Wlll pull uphaving plenty of timeto do so. and then when the break comes they will all let go. irrespective this? of the connections betweenthem.

Fig. 9 shows the trunking relay in addi- 'tion to the operating magnet O.- I have not deemed it necessary to show all the contacts on the 'arious relays employed in. my switches. since these may he of any well understood construction and are not claimed herein. j

Theswitch' shown in Figs. 7. 8. and 9 is typical. of the various switches employed.

It Will be'obserred. however. that there are only two series of contacts in the A switch. the series 1 of the typical switch together with its operating magnet 0 being omitted. while in the switch D there is ajourth series of contacts at lying immediately beneath the series 3 and whose wipers are moved simultaneously with the wipers ofseries 3. The controlling magnet X is also omitted from this switch since this is a connector switch and does not require an intermittently actuated magnet for selecting an idle trunk.

1 The operation of'rny system is as follows: The subscriber first depresses the button P which disconnects the telephone set bv (breaking the contacts 12 and p and grounds which inturn close the circuit of the trunln.

ing relay V throughthe following path: battery B, 20, m, m, 18, 2,41, 17, V, 21, to the opposite side of battery B. The relay V becoming energized closes the contacts a and '0 which serve to keep the relay energized after the wipers infseries 2 have left the a position and as long as there is a ground on No. 6 side of the line. The contacts v and vare disconnected, preventing a ground entering series 3 over wire 28. The energizing of the relay V causes series 2 to move to the ,clposition and if the first trunk happened tobe busy, as in this case we have shown it to-beby placing a ground on the contact leading to wiper .2 the magnet -X, which is connected to onesideof the battery through the constantly actuated commutator C,

" would become energized and cause series 3 to step around until an idle trunk was I found. The first. trunk being busy, the circuit of the magnet X is completed by the following path: battery B, 21, X, 23, 13, c, 2, 26, 2 to ground. After the trunking period is" passed, that is after the prolonged ground has been removed from No. 6 side of the line 3 at the substation the relay M'becomes deenergized and releases the magnet V which allows series 2 to fall back to the b or trunked through position. The calling subscriber is now connected through to the B switchby the-lfollowing path: lines 5 and 6, 2 and 2 2': and 28, z -and 2 1-5 and 16, to an idle B- switcln The calling subscriber now depresses the button P" which places ground 0% No. 6 side of the line by the fol- Zlowing path. ground, 1 p, 152 and 6. Ground is also placed on No. 5 side of the line by the following path: ground, 37, p 7), 151, 5. The contacts 72 and .p are vbrolie'nas are p and p", disconnecting the talking set; Ground now being placed on bothsidesof the line simultaneously, the re layE" becomes energized and attracting its armature, closes the contacts a and e which closes the-circuit of the operating magnet O by the following path: battery 13,0, 50,. 2 40, e e 46, to the opposite side of battery. The calling subscriber depresses the button Pa number of times corresponding to the thousands numeral of the desired line, and the relay E and the magnet O are operatedcorrespondingly. The operation of the magnet 0 causes the wipers in series 1 to step around the number of spaces corresponding to the thousands numeral of the line desired. After sending in the impulses net V as in the case ofthe A switch causes series 2 to takethe 0 position; When'the magnet vV is energized it closes-the contacts. o 'and a? maintaining its circuit through these so long as the ground is placed on No,

'6 side of the line. 5 If, after series 2 has assumed the c-position the first trunk happens to bebusy as. in this case I have shown-it to-be by placing a ground on the contact leading tothe wiper z, the; magnet X will become energized over theffollowing path: ground, 2, 33, 21 44, 2 c, 38, 49,

-V, 12, 0, 2 34, m and m to the opposite side of battery. The energizing of the mag X, 41, to battery. The relay X thereupom attracts its armature and closes'the contacts a: and w completing the circuit of the operating magnet O by the following path: battery B, O, 50, 2 39, :v, w, 41, to the opposite side of battery. The magnet X in operating closes the contacts a: and m which in turn closes the circuit of the -oper-- ating magnet O by the following path: bat tery B, 41, w, 0:, 39, 0, 2 50, O, to the. op-- ,po'site side of'battery. The energizing of the magnet O the second time instead of advancing series 1 as before now advances selies 3. -T his advance movement kept up so long as the circult of the magnet X is kept closed -by the wiper 2 finding a grounded or busy contact. As. soon as an idle or free contact is found the circuit of the magnet X is broken and. the contacts :0 and w are broken which stops the operation of the operating magnet O and the wipers of series 3 come to rest on an idle trunk in the desired thousand. After the trunking period, that is after ground is removed from No. 6 side of the line at the substation the relay M becomes deenergized,

the-wipers of series 2 assume the b position and the calling subscriber is connected through the A and B switches to the C switch. The circuit is as follows: 151, 5, Z .2 2 7, 2 15, 30, 22,2 13, 2,31, 2, 35 to the C switch, also 152,6, Z), 2 0, 0;, 28, 2 16, 29, 12,2 42 a, 4:5, .2 32, a, 36, and to the C switch. a

The nextstep in the order of calling will be for the calling subscriber to push the button P. the number of times corresponding to the hundred numeral 'of the desired line. The depressingof this button operates the relay E in the same manner that E" in the B switch was operated, in fact the operation of the G switch is identical in e .-*ery respect. with that of the switch. The relay E attracting its armature closes the contacts a and e which closes the circuit of the f=1spaces -oormasponding to' the hundred 'nuof the desired line. After sending in -the'--impulses torthe hundred numeral the 'si fissgriber' again depresses the button P groimdi'ng No. 6 side of the line which oper ates the magnet M closing the contacts m m which in turn closes the circuit of the trunking magnet V by the following pflfllf balltey. B, 62, -V?, 74,, a, 2 64, m, to'zthe ogipositeside of battery. The

of themagnet v as in the case 1 of'th'e A and B switch causes the series 2 to take {tlheic position. Whcn the' magnet V is energized at closes .the contacts a) and r -..asin-.this case I have maintaining its circuit through these so lon as ground is placed on No. 6 side of the line even after the wipers of series-2 have left the a position. If, after series 2.has assumed the :a position, the first trunk ihappens to be busy shown itto be by placing aground on the contact leading to "the wiper 2 "the magnet X will become energizedover the following path: ground,

.2 57, 2 7 1, 2 0,61, X :62 to the opposite side of battery. Therelay X thereupon contacts :2

' and 03 which in turn closes the circuit of the operating .'magnet O by the following path: battery 13,62, a2, 01 ,60, 0, 2 ,=66,-O", '68 to the opposite side of battery. The energizing of the magnet. O'this time instead of advancing series .1 as before now advances series 3. Thisadvance movement is kept up so long as -;is kept closed the circuit of the magnet X -'by-the wiye1' 2 finding a grounded or busy r contact. As soon as an idle or free contact is iound'the circuit of-the magnet X is broken as are the-contacts a1 and which stops-the operation of the operating magnet O and the Wipers of series 3 come to rest on an idle .5?

. trunk in the desired hundred. After the t-runking period, that is after ground is removed from No. '6 side. of the vlineat the substation the relay M becomes dener- "gized and the wipers of series 2 assume the 6 position and the calling subscriber is now connected through the A, B and C switches to the connector or D switch, by the following circuit: 35, 5'2, 7), 2 7O, 2-, 53, 2 55. into Fig. 5, 82 and M by parallel branches: also 36. 51, 6,2 72. '0 "u", 69, 2 54. .2 56, into Fig. 5, 81 and M by parallel branches,

the 'dividedflwindings of magnets .M and E? being bridged across the Wires 55 and 56 as shown in F ig. 5 and the WllS 81 and 82 constituting the talking circuit. The next .in the other switches.

desired lineT"Th e relay E magnet V step in the order of calling will be for the calling subscriber to push the button P. a number of times corresponding to the tens numeral of the desired line. The depressing of this button grounding both sides of the line'operates the relay E in the same manner the corresponding relays were operated The relay E attracting its armature closes the contacts a and e fiwhich in'turn completes the circuit of the operating magnet O by the following path: battery B, 95, O 91, a, 2 93, 6 e,

to the opposite side of battery. The opera- .tion of this magnet 0 causes the wipers in series 1 to step around a number of spaces corresponding to the tens numeral 015- the when: energized also breaks, the ci'mtacts e and e which jointly control the ircuit of the ringing relayY as will be explained later. Followr ing the sending in of the tens numeral is the usual't-rnnking period. The button P being depressed grounds No. 6 side of the line and operates the relay M which attracting its armature closes the contacts at and m com pleting the circuit of the trunking magnet V by the following path: battery B, 94, V a, 2 104., 92, m and m, 95, to the opposite sideof battery. The energizing of the in this case instead of advancing the series 2 two spaces as in the case of the former switches advances it but one space to the b position. The magnet V as in the case of the corresponding magnets in the other switches maintains its It will be noticed that the contacts occupying the posi tions a and b belonging to the wipers e and 2 are connected together. This is done to' allow the magnet 0 time for sending in the unit numeral of the desired line. The energizing of the relay M breaks the contacts m and m which jointly control the circuit f the ringing relay Y.

After the operation of the tens numeral 110 just described the ring wipers with reference to the bank .o'f contacts are disposed as shown in Fig. 6 except that they would reston the tens contact of all the numbers 'in a certain hundred. By the arrangement 115 of series 3 'being supplied with broad contacts eml'lracing four positions it is evident that the line connection will not be changed for the first tour successive impulses. The method of supplying generator current of 1 any frequency has been fully described. The nextstep in operation after the trunking period will be to send in the unit numeral of the desired line. The subscriber depressing the button P grounds both sides 12 of the line and operates the relay E which attracting its armature closes the contacts e? and e completing the circuit of-the magnot 0 as before. This time the magnet 0 instead of advancing the series 1 advances 139 circuit through the closing of the contacts 0 and '0 to be operated a second This circuit-will be maintained after the series 3 a number ofspac'es corresponding to the unit numeral of the desired line. After the unit numeral has been transmittedthe regular trunking period follows. The subscriber depressing the button I grounds No. 6 side of theline operating the relay i 3 which closes the contacts. m and m operating thev trunking magnet V? as before. The

trunking r'nagnet V this time instead of a'dyancing'series Qbut one space steps it up two spaces or to the (Z position. This position is I the test position for determining Whether.

the; line-called for is busy; If the line is busy the following conditions will prevail: The contacts occupied by the wiper '2 will be grounded as I haye' shown it in this case for illustration. The-ground. beingon the desired contact will complete the followingcii'cuit'z'ground, 2 85 ,100,2 d, 89, d, 2 104, 41 ,41 105, 7 ,94, to main battery B.

trur'iking period atthe phone is broken, that is after the'button-P isfrelea sed and'will be maintained so long as the line is held busy. 'While thisline is held busy we have the following circuit from the busy generator G ground: G? 7 7 0 2377 i 1 y, l/ L, 82, 55, and continued through the other switches through the calling subscribers telephone to ground. The subscriber receivjingthis signal knows the line called for is bus If however, the line called for is not busy,. hen serih's 2 will return to the positioncinflthe same manner as the A, B and C switchestrpturn to the 6 position. \Ve now have the trunlred-through or connected'position. The calling station now has connection with the line of the called station and has upon the'ringin relay the proper generator current for ringing the station de sired. The subscriber now depresses the ringing button P". It will be noticed that the current supply forthe transmitter is suppliedover both sides of the line to ground through the M and E relays ofjthe various switches. The'battery supply fromNo. 5 side of the line through the transmitter cinv cuit is as follows: 5, 151, p, 79 154:, 72 p 15 7, 156, 72,, 79,158, through one winding ofthe retardation coil N, p, H, h, primary of the. induction coil I, transmitter T to ground. The battery supply from No. 6 side of the line'is as follows 152, pa, p, 153, p,

p, 155,'throughone winding of the retardationcoil N, p p, H, h, primary of the induct-ion coil-I, transmitter T to ground,

So-lon'gas this circuit'is maintained through both sides of the line to groi1nd.tliroi1gli'tlie transmitter T, the E relays of the various switches are energized and attract their armatures. p The subscriber 1n depre'ssingthe button I for ringing, disconnects ground fromboth, sides ofthe line and the relays of the carious switches will. become deenergized. The relay E in connector switch D becoming deener'gized, closes thecontacts 6 and .6 completing the circuit of the ringing relay Y by the following path: bat-- 95, to the opposite side ofbattery'. I'Iheringing relay Y now being energizedattracts its armature, breaks the cont-acts y a and; 'y"y and makes. the contacts g y'-, and 3 placing generator current on the privatelnorinals to the called subscribers telephone overNo.- 6 sideof the line by the following'path: G, 118, a,-].O6,y', y,

86, a, 23?, 103, 12 Jfl-lOQ, 2 84, 2 private 4 normal 24, and in Fig. 2, 2 Z), 9, P, e*, 8, to

'No. 6'side ofthe line to the called 'subscriber; and oyer No: 5'side of the: line by the following path; G, 10 8, 2 ,107., 11/ y,

.87, a, 2 101,2 83, 2 private normal 25;

stead of the generator current going over the private nornial's24 and 25 to the calling line it would go out over another pair of private normals. belonging to theparticular line called for. At the'end of the conversation the calling party depresses the'buttm P? placing'a ground oil-No.1 5 side of the line which energizes the M and .E relays of the various switches which attracting their armatur'es close the circuits 01E their respective release magnets \V' which restores-the switches and all'their parts. For tracing the circuit of the release niagnet wewill follow out that of W in the connector switch D whose circuit is closed by the'followingpath: battery B, 6 e 93,VV 92.

The circuits of the release magnets of the her and need not be described.

No busy signal hasbeen provided for lines.

that have called, as for example an operated- A- switch. This has not been deemed neces; sary .because special means have-been girovidedin the'eutoif springs, e e and 03 .33. When switch A has operated, the normal lines 24 and 25 connected through 2'' and b and-6,9 and 1O,e and e? are disconnected from s and e? which normally connect with "5 and .6 through 7 and 8, for be'itrem'eIm bered that 'E-is energized during conversation. For a party callingba-ckon his own line,- thisjopen normal circuitjat efl'e -and e, 6? does notinterfere, inasmuchas' the other switches are operated in the satne man- 110 m, m", .95, to the'opposite side -of 'bat-tery.

party called is directly on the same line 56,

and as for ringing, where button p is pressed the ground is removed from the line 5-6, the relay t is deenergized, and springs 0 e and e, 6 close, permitting the ringing current to pass over 'to line 5- 6. The only busy test is provided in the connector switch as previously set forth. The connector does not automatically release from a busy line.

Having thus described my in 'ention, what I claim and desire to secure by Letters Patent is:

1. In a telephoneexchange system, a sub station and a central station and a metallic line-circuit interconnecting them, means at the sub-station for separately grounding the two sides of the line, means to simultaneously ground both sides of the line, switching means at the central station and controlling magnets therefor, having their.

windings directly connected to the line, one

of said magnets wound and connected -so that it will respond only to simultaneous grounding of both sides of the line, and another magnet wound and connected so that it will respond only to grounding of one,

side, whereby the switch may be controlled as desired, and substantially as described. 2. In a telephone exchange system, a sub station and a central station anda metallic line-circuit interconnecting them,;m'eans for producing current changes in either or both sides of the line, switching apparatusat the central station for interconnecting the subscribers lines, and controlling magnets for said switching apparatus, one of said magnets responsive to current changes in one side of line, and another of said magnets ir-- responsive thereto, both magnets, however, being responsive to current changes in the other side of line, whereby one magnet may be actuated separately, or both magnets may be actuated together, substantially as described.

3. In a telephone exchange system, a subscribers'station and a central station anda metallic line-circuit interconnecting'them, means for producing current. changes in either or both sides of the line, switching apparatus atthe central station for interconnecting the subscribers lines, and con.-

trolling magnets for said switching appara-- tus, one. magnet responsive to current changes in either side of line, but irresponsive to simultaneous changes in both sides,

the other magnet irresponsive to changes in one side of the line, but responsive to changes in the other side or in both sides, whereby with the two magnets three changes in control maybe obtained, one by the energization ofone magnet separately, another by the :energization of the other magnet separately, and a thirdby the energization o'f'both magnets, or their deia'ner-o gizations in the order stated, substantially as described.

4. In a telephone exchange system, a subscribers station and a central station and a 'metallic line-circuit interconnecting them, switching apparatus at the central station for interconnecting the su s ribers lines,

para-tus, one of said magnets bridged across with respect to current in the same direction through both sides-of the line, another of said magnets also connected in a bridge on the line and having-its win dings so laid on in both sides of the line, but irresponsive to current in one side only,-substantially as described.

5. In a telephone exchange system, a subscribers station and a central. station and a metallic line-'circuit interconnecting them, switching apparatus at the central station for interconnecting the subscribers" lines, controlling magnets for said switching apthe line and having its windings differential with respect-to. current in thesame'direction through both. sides of the 'line, another of said magnets also connectedin abridge on. theiline and having a plurality of windings so laid on, pl oportioned and connectedto'th respective line wires as to make the magnet responsive to current in the'same directidn rent in one side, but responsive to current in the other side, .whereby the first magnet may be separately controlled, orthe second magsubstantially as overbalance and operatively -;energ i'ze the magnet; one of the first two parts being.

third part from their point of union to hattery or ground,-substantially 'as described.

7. In a telephone exchange system, a sub- ;station and a central station and a metallic line-circuit interconnecting them, means for and so proportioned as to make the magnetresponslve to current in the same direction ,pa-ratus, one'of said magnets bridged across net may be separately controlled, or both each other, and the third part suflicient to connected to each side of the line, and the controlling magnets for said-switching apthe line and having its windings diflerential in both sides of. the line, irresponsive to cur- 

